The present invention relates generally to aircraft collision avoidance systems, and particularly, to displaying air traffic information on a Traffic Alert and Collision Avoidance System, or TCAS.
Aircraft pilots are expected to visually identify collision threats and avoid them. This xe2x80x9csee and avoidxe2x80x9d technique based on the pilot""s visual sense remains the most basic method of aircraft collision avoidance. However, since the 1950""s electronic techniques based on radio frequency and optical transmissions have been developed to supplement the pilot""s visual sense. The government has developed and implemented a system of ground based and aircraft carried equipment designated the Air Traffic Control Radar Beacon System (ATCRBS). This system includes two different types of ground based radar emitters located at each of a plurality of Air Traffic Control (ATC) stations. One type of radar is referred to as the Primary Surveillance Radar (PSR), or simply as the primary radar. The primary radar operates by sending out microwave energy that is reflected back by the aircraft""s metallic surfaces. This reflected signal is received back at the ground radar site and displayed as location information for use by an air traffic controller. The second type of radar is referred to as the Secondary Surveillance Radar (SSR), or simply secondary radar. Unlike the primary radar, the SSR is a cooperative system in that it does not rely on reflected energy from the aircraft. Instead, the ground based SSR antenna transmits a coded 1030 MHz microwave interrogation signal. A transponder, i.e., a transmitter/receiver, carried on the aircraft receives and interprets the interrogation signal and transmits a 1090 MHz microwave reply signal back to the SSR ground site. This receive and reply capability greatly increases the surveillance range of the radar and enables an aircraft identification function, referred to as Mode-A, wherein the aircraft transponder includes an identification code as part of its reply signal. This identification code causes the aircraft""s image or blip on the ATC operator""s radar screen to stand out from the other targets for a short time. Thus, Mode-A provides an rudimentary identification function.
In addition to the identification function provided by Mode-A, the aircraft altimeter data are typically passed to the transponder such that a reply signal includes altitude information, referred to as Mode-C.
A ground based SSR sequentially transmits both Mode-A and Mode-C interrogation signals to aircraft in the area. Accordingly, the interrogation signal transmitted by the SSR contains three pulses. The second pulse is a side-lobe suppression signal transmitted from an omnidirectional antenna collocated with a mechanically rotating antenna which provides a highly directive antenna beam. The first and third pulses are transmitted by the directive antenna at a predetermined frequency and are separated by a predetermined interval. The time interval between the first and third pulses defines what information the interrogator is requesting: eight (8) microseconds for identification and twenty-one (21) microseconds for altitude. The operator of the ground based SSR sets the radar interrogation code to request either Mode-A or Mode-C replies from the aircraft transponder. Typically, the radar is set to request a sequence of two Mode-A replies followed by a single Mode-C reply. This sequence is repeated so that a radar operator continuously receives both the Mode-A identification code and the Mode-C altitude information. Upon receipt of the interrogation signal, the aircraft transponder develops and transmits a reply signal which includes the identification or altitude information. The ground based SSR receives and processes the transponder reply signal, together with time of arrival range information, to develop a measurement of position for each responding aircraft. Under such a system, the air traffic controller uses this information to involve the aircraft by radio, usually with voice communication, to maintain or restore safe separations between aircraft. The system is inherently limited because each aircraft needs be dealt with individually, which requires a share of the air traffic controller""s time and attention. When traffic is heavy, or visibility is low, collision potential increases.
During the 1960""s the increases in the number of aircraft, the percentage of aircraft equipped with transponders, and the number of ATCRBS radar installations began to overload the ATCRBS system. This system overload caused a significant amount of interference and garble in the Mode-A and Mode-C transmissions because of replies from many simultaneously interrogated aircraft. Furthermore, the Mode-A and Mode-C systems are unable to relay additional information or messages between the ground based SSR and the interrogated aircraft, other than the aforementioned identification and altitude information. The Mode Select, or Mode-S, was the response to this overload and other deficiencies in ATCRBS. Mode-S is a combined secondary surveillance radar and a ground-air-ground data link system which provides aircraft surveillance and communication necessary to support automated ATC in the dense air traffic environments of today.
Mode-S incorporates various techniques for substantially reducing transmission interference and provides active transmission of messages or additional information by the ground based SSR. The Mode-S sensor includes all the essential features of ATCRBS, and additionally includes individually timed and addressed interrogations to Mode-S transponders carried by aircraft. Additionally, the ground based rotating directive antenna is of monopulse design which improves position determination of ATCRBS target aircraft while reducing the number of required interrogations and responses, thereby improving the radio frequency (RF) interference environment. Mode-S is capable of common channel interoperation with the ATC beacon system. The Mode-S system uses the same frequencies for interrogations and replies as the ATCRBS. Furthermore, the waveforms, or modulation techniques, used in the Mode-S interrogation signal were chosen such that, with proper demodulation, the information content is detectable in the presence of overlaid ATCRBS signals and the modulation of the downlink or reply transmission from the transponder is pulse position modulation (PPM) which is inherently resistant to ATCRBS random pulses. Thus, the Mode-S system allows full surveillance in an integrated ATCRBS/Mode-S environment.
The Radio Technical Commission for Aeronautics (RTCA) has promulgated a specification for the Mode-S system, RTCA/DO-181A, MINIMUM OPERATIONAL PERFORMANCE STANDARDS FOR AIR TRAFFIC CONTROL RADAR BEACON SYSTEM/MODE SELECT (ATCRBS/MODE-S) AIRBORNE EQUIPMENT, issued January 1992, and incorporated herein by reference. According to RTCA specification DO-181A, the airborne portion of the Mode-S system includes in one form or another at least a dedicated transponder, a cockpit mounted control panel, two dedicated antennas and cables interconnecting the other elements. As discussed more fully below, each aircraft may be within range of more than one SSR ground station at any time and must respond to interrogation signals broadcast from multiple directions. Therefore, the Mode-S system typically uses two single element omnidirectional antennas to receive interrogation signals from any quadrant and reply in kind.
In operation, a unique 24-bit address code, or identity tag, is assigned to each aircraft in a surveillance area by one of two techniques. One technique is a Mode-S xe2x80x9csquitterxe2x80x9d preformed by the airborne transponder. Once per second, the Mode-S transponder spontaneously and pseudo-randomly transmits, or xe2x80x9csquitters,xe2x80x9d an unsolicited broadcast, including a specific address code unique to the aircraft carrying the transponder, via first one and then the other of its antennas which produce an omnidirectional pattern. The transponder""s transmit and receive modes are mutually exclusive to avoid damage to the equipment. Whenever the Mode-S transponder is not broadcasting, it is monitoring, or xe2x80x9clistening,xe2x80x9d for transmissions simultaneously on its omnidirectional antennas. According to the second technique, each ground based Mode-S interrogator broadcasts an ATCRBS/Mode-S xe2x80x9cAll-Callxe2x80x9d interrogation signal which has a waveform that can be understood by both ATCRBS and Mode-S transponders. When an aircraft equipped with a standard ATCRBS transponder enters the airspace served by an ATC Mode-S interrogator, the transponder responds the with a standard ATCRBS reply format, while the transponder of a Mode-S equipped aircraft replies with a Mode-S format that includes a unique 24-bit address code, or identity tag. This address, together with the aircraft""s range and azimuth location, is entered into a file, commonly known as putting the aircraft on roll-call, and the aircraft is thereafter discretely addressed. The aircraft is tracked by the ATC interrogator throughout its assigned airspace and, during subsequent interrogations, the Mode-S transponder reports in its replies either its altitude or its ATCRBS 4096 code, depending upon the type of discrete interrogation received. As the Mode-S equipped aircraft moves from the airspace served by one ATC Mode-S interrogator into that airspace served by another Mode-S interrogator, the aircraft""s location information and discrete address code are passed on via landlines, else either the ground based SSR station picks up the Mode-S transponder""s xe2x80x9csquitterxe2x80x9d or the Mode-S transponder responds to the All-Call interrogation signal broadcast by the next ATC Mode-S interrogator.
The unique 24-bit address code, or identity tag, assigned to each aircraft is the primary difference between the Mode-S system and ATCRBS. The unique 24-bit address code allows a very large number of aircraft to operate in the air traffic control environment without an occurrence of redundant address codes. Parity check bits overlaid on the address code assure that a message is accepted only by the intended aircraft. Thus, interrogations are directed to a particular aircraft using this unique address code and the replies are unambiguously identified. The unique address coded into each interrogation and reply also permits inclusion of data link messages to and/or from a particular aircraft. To date, these data link messages are limited to coordination messages between TCAS equipped aircraft, as discussed below. In future, these data link messages are expected to include Aircraft Operational Command (AOC) information consisting of two to three pages of text data with flight arrival information, such as gates, passenger lists, meals on board, and similar information, as well as Flight Critical Data (FCD). However, the primary function of Mode-S is surveillance and the primary purpose of surveillance remains collision avoidance.
The transponder reply emissions from the ATCRBS, including Mode-S, described above alone provide the only information for locating and identifying potential threats. While such responsive systems tend to be simple, relatively low cost, and do not crowd the spectrum with additional RF transmissions, detection of transponder emissions from other aircraft is difficult. The government and aviation industry have cooperated in developing Operational Performance Standards for a Traffic Alert and Collision Avoidance System, known as TCAS, separate from the ATCRBS/Mode-S transponder system. The standards are set forth in the RTCA specifications DO-185, MINIMUM OPERATIONAL PERFORMANCE STANDARDS FOR AIR TRAFFIC ALERT AND COLLISION AVOIDANCE SYSTEM (TCAS) AIRBORNE EQUIPMENT, issued Sep. 23, 1983, consolidated Sep. 6, 1990, and DO-185A, MINIMUM OPERATIONAL PERFORMANCE STANDARDS FOR AIR TRAFFIC ALERT AND COLLISION AVOIDANCE SYSTEM II (TCAS II) AIRBORNE EQUIPMENT, issued December 1997, both of which are incorporated herein by reference.
FIG. 1 illustrates one known embodiment of the TCAS 1 having 4-element interferometer antennas 2A and 2B coupled to a radio frequency receiver 3 of a TCAS processor 4. Receiver 3 is coupled in turn to a signal processor 5 operating known traffic alert and collision avoidance software. A radio frequency transmitter 6 is coupled to signal processor 5 for broadcasting Mode-S interrogation signals. An associated control panel 7 for operating TCAS 1 and display 8 for displaying TCAS information are each coupled to signal processor 5 of TCAS processor 4, as described in each of U.S. Pat. No. 4,855,748 entitled, TCAS BEARING ESTIMATION RECEIVER USING A 4 ELEMENT ANTENNA, issued on Aug. 8, 1989, to Ruy L. Brandao et al and U.S. patent application Ser. No. 09/369,752 entitled, MULTIFUNCTION AIRCRAFT TRANSPONDER, filed on Aug. 6, 1999, in the names of Daryal Kuntman, Ruy L. Brandao, and Ruy C. P. Brandao, the complete disclosures of which are incorporated herein by reference. TCAS is a well-known active collision avoidance system that relies upon reply signals from airborne transponders in response to interrogation signals from an aircraft equipped with an ATCRBS Mode-A/Mode-C or Mode-S transponder. The TCAS antenna is driven to produce a directional microwave transmission, or radiation, pattern carrying a transponder generated coded interrogation signal at 1030 MHz, the same frequency used by ground based SSR stations to interrogate Mode-S transponders. Whenever the TCAS transponder is not broadcasting, it is xe2x80x9clisteningxe2x80x9d for Mode-S xe2x80x9csquittersxe2x80x9d and reply transmissions at 1090 MHz, the same frequency used by Mode-S transponders to reply to interrogation signals. Thus, a TCAS equipped aircraft can xe2x80x9cseexe2x80x9d other aircraft carrying a transponder. Once a transponder equipped target has been xe2x80x9cseen,xe2x80x9d the target is tracked and the threat potential is determined by operation of known TCAS algorithms, as described in each of U.S. Pat. No. 5,077,673, AIRCRAFT TRAFFIC ALERT AND COLLISION AVOIDANCE DEVICE, issued Dec. 31, 1991, and U.S. Pat. No. 5,248,968, TCAS II PITCH GUIDANCE CONTROL. LAW AND DISPLAY SYMBOL, issued Sep. 28, 1993, the complete disclosures of which are incorporated herein by reference. Altitude information is essential in determining a target""s threat potential. As described in incorporated U.S. Pat. No. 5,077,673 and U.S. Pat. No. 5,248,968, comparison between the altitude information encoded in the reply transmission from the threat aircraft and the host aircraft""s altimeter is made in the TCAS processor and the pilot is directed obtain, a safe altitude separation by descending, ascending or maintaining current altitude.
Collision avoidance is enhanced by including range information during threat determination. The approximate range, or distance between the host aircraft and the target, is based on the elapsed time from transmission of the interrogation signal by the host aircraft to receipt of the responsive transponder signal from the target aircraft
Knowledge of the direction, or bearing, of the target aircraft relative to the host aircraft""s heading greatly enhances a pilot""s ability to visually acquire the threat aircraft and provides a better spatial perspective of the threat aircraft relative to the host aircraft. The TCAS processor can display bearing information if it is available. Directional antennas are used in some TCAS systems for determining angle of arrival data which is converted into relative bearing to a threat aircraft by the TCAS processor. Several methods exist for determining angle of arrival data. One common arrangement uses a phase matched quadrapole antenna array with output signals being combined such that the phase difference between two output ports of the combining circuitry indicates the bearing of a received transponder signal. Another method for determining angle of arrival data includes a method based on signal phase, commonly known as phase interferometry. Still another commonly known method is based on signal amplitude. Attenuation of the received transponder signals by the airframe blocking the antenna from the transmitter is often overcome by locating a primary directional antenna on a top surface of the aircraft and a second antenna on a bottom surface of the aircraft. The second or bottom antenna is sometimes omnidirectional which reduces cost at the expense of reduced directional coverage. Other TCAS systems provide duplicate directional antennas top and bottom. U.S. Pat. No. 5,552,788, ANTENNA ARRANGEMENT AND AIRCRAFT COLLISION AVOIDANCE SYSTEM, issued Sep. 3, 1996, the complete disclosure of which is incorporated herein by reference, teaches an arrangement of four standard monopole antenna elements, for example, xc2xc wavelength transponder antennas, arranged on opposing surfaces of one axis of the aircraft at the extremes of two mutually orthogonal axes to avoid shadowing and provide directional information about the received reply signal. For example, two monopole antennas are preferably mounted on a longitudinal axis of the aircraft and two additional monopole antennas are preferably mounted on a lateral axis of the aircraft orthogonal to the longitudinal axis passing through the first two antennas. Directionality is determined by comparing the power levels of the received signals. Additionally, U.S. Pat. No. 5,552,788 teaches a TCAS system which can transmit transponder interrogation signals directionally using predetermined ones of the monopole antennas, thus eliminating dependence upon ground based radar systems for interrogating threat aircraft transponders.
Other antennas for directionally transmitting TCAS system transponder interrogation signals are also commercially available. For example, a TCAS system-compatible directional antenna is commercially available from Honeywell International, Incorporated of Redmond, Washington, under the part number ANT 81A.
The ATCRBS/Mode-S surveillance system and the TCAS collision avoidance system are generally separate, the algorithms operated by the TCAS processor account for the data provided by the intruder aircraft to determine what evasive maneuver to recommend to the host aircraft""s pilot, i.e., whether to recommend that the pilot maintain current altitude, ascend or descend. The TCAS system also uses the inter-aircraft data link provided by the addressable Mode-S transponder to coordinate the recommended evasive maneuver with a TCAS and Mode-S equipped intruder aircraft. Furthermore, a connection between the TCAS and Mode-S transponders and other avionics on an aircraft allows coordination between the TCAS and Mode-S transponders.
The TCAS is also coupled to provide an output signal to one or more displays as described in above incorporated U.S. patent application Ser. No. 09/369,752. The challenge of any traffic depiction is reducing 3-dimensional data into a 2-dimensional display. The function of the display is generally to visually define the level of threat posed by a given intruder, as well as the intruder""s vertical position and motion relative to the host aircraft. Current traffic displays show the relative horizontal and lateral positions of conflicting traffic graphically, while relative vertical positions are depicted numerically.
FIG. 2 shows one configuration of a conventional display 10 used with a TCAS collision avoidance system. Display 10 includes an aircraft symbol 12 to depict the position of the host aircraft. A circle, formed by multiple dots 14 surrounding host aircraft position symbol 12, indicates a 2 nautical mile range from the host aircraft. Generally, semi circular indicia 16 around the periphery of indicator display 10 and a rotatable pointer 18 together provide an indication of the vertical, i.e., altitude, rate of change of the host aircraft. Indicia 16 are typically marked in hundreds of feet per minute.
Other target aircraft or xe2x80x9cintrudersxe2x80x9d are identified on display 10 by indicia or xe2x80x9ctagsxe2x80x9d 20, 22 and 24. Tags 20, 22, 24 are shaped as circles, diamonds or squares and are color coded (not shown) to provide additional information. Square 20 colored red represents an intruder entering warning zone and suggests an immediate threat to the host aircraft with prompt action being required to avoid the intruder. Circle 22 colored amber represents an intruder entering caution zone and suggests a moderate threat to the host aircraft recommending preparation for intruder avoidance. Diamond 24 represents near or xe2x80x9cproximate trafficxe2x80x9d when colored solid blue or white and represents more remote traffic or xe2x80x9cother trafficxe2x80x9d when represented as an open blue or white diamond. Air traffic represented by either solid or open diamond 24 is xe2x80x9con filexe2x80x9d and being tracked by the TCAS.
Each indicia or tag 20, 22, 24 is accompanied by a two digit number preceded by a plus or minus sign. In the illustration of FIG. 2 for example, a xe2x80x9c+05xe2x80x9d is adjacent circle tag 20, a xe2x80x9cxe2x88x9203xe2x80x9d is adjacent square tag 22 and a xe2x80x9cxe2x88x9212xe2x80x9d is adjacent diamond tag 24. Each tag may also have an vertical arrow pointing either up or down relative to the display. The two digit number represents the relative altitude difference between the host aircraft and the intruder aircraft; the plus and minus signs indicating whether the intruder is above or below the host aircraft. Additionally, the two digit number appears positioned above or below the associated tag to provide a visual cue as to the intruder aircraft""s relative position: the number positioned above the tag indicates that the intruder is above the host aircraft and the number positioned below the tag indicates that the intruder is below the host aircraft. The associated vertical arrow indicates the intruder aircraft""s altitude is changing at a rate in excess of 500 feet per minute in the direction the arrow is pointing. The absence of an arrow indicates that the intruder is not changing altitude at a rate greater than 500 feet per minute.
Display 10 includes several areas represented by rectangular boxes 26, 28, 30, 32, 34 which are areas reserved for word displays wherein conditions of the TCAS are reported to the pilot of the host aircraft. For example, if a portion or component of the TCAS fails, a concise textual report describing the failure appears in one of rectangular boxes 26, 28, 30, 32, 34. In another example, if the operator operates mode control 36 to select one of a limited number of operational modes, a concise textual message indicating the choice of operational mode appears in another of rectangular boxes 26, 28, 30, 32, 34. Selectable operational modes typically include a xe2x80x9cstandbyxe2x80x9d mode in which both of the host aircraft transponder systems are inactive, a xe2x80x9ctransponder onxe2x80x9d mode in which a selected one of primary transponder and secondary transponder is active, a xe2x80x9ctraffic alertxe2x80x9d mode in which an alert is transmitted to the host aircraft pilot if any Mode-C or Mode-S transponder equipped aircraft are entering a first predetermined cautionary envelope of airspace, and a xe2x80x9ctraffic alert/resolution advisoryxe2x80x9d mode in which a traffic alert (TA) and/or resolution advisory (RA) is issued if any Mode-C or Mode-S transponder equipped aircraft are entering a second predetermined warning envelope of airspace. The various operational modes described above are selectable by operating mode control 36.
The Vertical Speed Indicator (VSI) portion of indicator display 10, formed by the semi circular indicia 16 around the periphery and rotatable pointer 18, are used in the TCAS to indicate a rate of climb or descent that will maintain the safety of the host aircraft. In the particular example of FIG. 2, a colored arc portion 40, referenced by double cross-hatching, of the VSI scale indicates a recommended rate of climb intended to ensure the safety of the host aircraft. Another colored arc portion 42, referenced by single cross-hatching, of the VSI scale indicates a rate of descent which the TCAS recommends against for the host aircraft in the current situation. The operator of the intruder aircraft receives instructions coordinated with the host aircraft TCAS.
The TCAS and Mode-S sensor and datalink technologies described above enable displays to provide information both internal and external to the aircraft. Such enhancements to pilot situation awareness are normally expected to provide the pilot with better situation awareness which should serve as a basis for more accurate decisions.
While TCAS represents one known system for predicting airborne collisions, other predictive systems are also known. For example, U.S. Pat. No. 5,325,302, entitled GPS-BASED ANTI-COLLISION WARNING SYSTEM, issued to Izidon, et al on Jun 28, 1994, the complete disclosure of which is incorporated herein by reference, describes a method for predicting a collision between two or more relatively moving aircraft, including determining a respective position in space for each one of the aircraft relative to a fixed frame of reference at a predetermined frequency to produce successive frames of positional data for each aircraft with a coupled memory for storing the successive positional data frames, computing a trajectory for each aircraft relative to the fixed frame of reference, and predicting whether two or more trajectories will intersect.
Currently, vertical maneuver information to avoid collision with an intruder aircraft is provided either on an Attitude Direction Indicator (ADI) of an Electronic Flight Instrument System (EFIS) or via rate of climb information on a VSI portion of indicator display 10 (shown in FIG. 2). However, TCAS and other known systems for predicting airborne collisions allow aircraft to approach one another to within as little as 35 seconds or less of a potential collision before collision avoidance maneuver information is displayed to the host aircraft flight crew.
Thus, while TCAS and other ways to predict collisions are known, none provides a practical method and apparatus for effectively predicting and displaying long-range collision information. As aircraft maneuver to avoid weather and terrain, they are often funneled into the same segment of airspace. This is especially so in regions with vertical terrain development, which is also conducive to dangerous convective weather development.
Therefore, long-range detection and management of potential collisions would be highly beneficial to flight crews attempting to coordinate their maneuvers with other aircraft in uncontrolled airspace. Furthermore, present visual flight displays fail to include visual representation of vertical separation. Therefore, vertical profile display of traffic data, in contrast to the current horizontal profile displays, would also be of great value for long-range detection and management of potential collisions.
FIG. 3 illustrates the vertical profiling currently used in various ground proximity warning devices and weather radar systems to provide the flight crew with the entire weather situation along the intended direction of flight. FIG. 3 illustrates a relatively large angle vertical profile scan 50 developed along the flight path as provided by a commercial weather radar system available from Honeywell International, Incorporated of Morristown, N.J. In contrast, other weather radar systems provide the conventional azimuth scan 52. However, although vertical profile scan 50 provides a vertical view 54 of the situation ahead of the aircraft 100 in contrast to the conventional horizontal view 56 provided by other radar systems, vertical view 54 is a planar view showing conditions within a narrow vertical slice of the flying space directly ahead of the host aircraft 100. An Enhanced Ground Proximity Warning System (not shown) also commercially available from Honeywell International, Incorporated, also provides a vertical view (not shown) that is a planar view showing the situation ahead of aircraft 100. However, these 2-dimensional vertical planar views are not currently capable of showing traffic information, except as exists within the vertical plane of interest. Thus, the traditional horizontal traffic information is omitted from current 2-dimensional vertical profile views while ground proximity or weather radar information are displayed.
Therefore, a means for reducing 3-dimensional traffic data into a 2-dimensional vertical profile view and displaying the situational awareness information in a 2-dimensional display is desirable.
The present invention overcomes the limitations of the prior art by providing a method and device for reducing 3-dimensional traffic data into a 2-dimensional vertical profile view and displaying the situational awareness information in a 2-dimensional display. According to one aspect of the invention, conventional horizontal display symbology and processes are utilized, thereby maximizing commonality and avoiding costly retraining of flight crews to interpret data in a new fashion. Furthermore, the method and circuit of the present invention are applicable to TCAS or ACAS (Airborne Collision Avoidance System) and to all aerial traffic detection and collision avoidance systems.
Vertical profiling allows flight crews to plan and coordinate maneuvers relative to other aircraft, weather, and terrain. Vertical profiling is especially useful in regions with vertical terrain development, which also is conducive to convective weather development. As aircraft maneuver to avoid the weather and terrain, they are often funneled into the same segment of airspace. The vertical profile depictions of the invention enable flight crews to more effectively and safely interpret traffic data.
The vertical profile traffic data depictions of the invention are also of great value for long-range detection and management of potential collisions. The vertical profile depictions of the invention enable flight crews to coordinate their maneuvers with other aircraft in uncontrolled airspace, often while still more than 100 miles apart. By coordinating actions at such great distances, flight crews are provided ample time to ensure that their actions maintain minimum separation. Thus, when implemented in a TCAS, the long-range vertical profile traffic data of the invention provide a strategic traffic avoidance tool in contrast to the tactical information provided by conventional systems. The information provided by the invention allows he flight crew to develop a planned response to traffic information in advance of a collision situation simply by slight speed adjustments and/or course alternations, in contrast to the immediate responses required by a TCAS traffic alert (TA) or resolution advisory (RA). Safety is enhanced because collision situations are avoided at distances well beyond the traditional TA and RA thresholds. Furthermore, fuel savings and passenger comfort are enhanced when the flight crew can respond to a potential collision situation by throttling back slightly or altering course slightly to avoid a potential collision situation, rather than having to waste fuel and disturb passengers by suddenly performing a climb or descent when a collision situation is encountered.
The method of the present invention is a method for displaying vertical situational awareness information relative to an aircraft hosting equipment implementing the method, the method includes defining a three-dimensional sampling reference frame relative to the host aircraft; defining a vertical sampling volume encompassing a predetermined volume of airspace; applying the vertical sampling volume to a sampling reference frame defined relative to the host aircraft; and detecting other aircraft within a predetermined range of the host aircraft. Furthermore, the method of the invention includes determining a position of other aircraft relative to the sampling volume; and, for each of said other aircraft positioned within the sampling volume, displaying in a two-dimensional vertical profile view a symbol representing a three-dimensional position of the other aircraft. Preferably, the position information of the other aircraft includes range and altitude information relative to the host aircraft.
According to one aspect of the invention, the symbol representing a 3-dimensional position of said other aircraft within said sampling volume further is displayed in a 2-dimensional position that is clearly and unambiguously representative of the 3-dimensional position of the other aircraft relative to the host aircraft.
According to another aspect of the invention, the method of the invention includes determining a potential conflict with one or more of the other aircraft. Preferably, when such a potential conflict is determined, the symbol representing a 3-dimensional position of the other aircraft is highlighted. Such highlighting is accomplished, for example, by any of: changing the color of the symbol representing the intruder aircraft, changing the shape of the symbol, periodically highlighting the symbol by xe2x80x9cflashingxe2x80x9d the symbol, framing or xe2x80x9coutliningxe2x80x9d the symbol, and displaying the symbol within a conflict range box displayed at an estimated range of the potential conflict.
According to still another aspect of the invention, the invention determines potential conflicts with other aircraft positioned within the sampling volume and/or other aircraft positioned outside of the sampling volume.
According to yet another aspect of the invention, the method of the invention also displays a maneuver useful for avoiding the potential conflict. For example, the pilot is directed change speed or obtain a safe altitude separation by descending, ascending or maintaining current altitude.
According to other aspects of the invention, potential conflicts with other aircraft are determined relative to the current track or the planned flight path of another aircraft. Preferably, the potential conflict is also determined relative to either the current track or the planned flight path of the host aircraft.
According to still other aspects of the invention, the method of the invention is implemented in an electronic circuit having a memory for storing multiple machine instructions and a processor coupled to the memory and executing the machine instructions to implement multiple functions of the invention. According to various aspects of the invention, the functions include: accessing a signal processed as situational awareness information relative to the host aircraft; defining the situational awareness information relative to a vertical sampling volume defined relative to the host aircraft; transposing the situational awareness information into a vertical profile view relative to the vertical sampling volume; and generating a video signal of the vertical profile view of the situational awareness information.
According to one aspect of the invention, the situational awareness information includes position information of other aircraft relative to the host aircraft, and further includes potential conflict information.
According to another aspect of the invention, the functions executed by the circuit of the invention also include a function determining conflict solution information relative to such potential conflicts. Preferably, the video signal generated by the circuit also includes such conflict solution information.
According to yet anther aspect of the invention, the circuit of the invention includes a display adapted to receive the video signal and able to generate a 2-dimensional display of the situational awareness information.